Hi Lewis, On Tue, Mar 20, 2012 at 2:42 AM, Oldrine Lewis <[email protected]> wrote: > Hi, > > I am a little confused too cos the FCS check should be automatically done in > the extended mode. > > The corrupted packet I noticed had an incorrect length (argument in > Receive() event signalled in the app) and also some of the data bytes were > corrupted. I have not yet been able to capture another corrupted packet > since.
With very low probability a corrupted packet can still pass the CRC check, maybe you have seen one. Would be nice to know if it would have passed a manual CRC check. > Today, I noticed that I was losing a few packets, which I think was due to > another Interrupt arrving from the RF230 (crcValid = ! radioIrq;). This > however did not result in a corrupted packet. > > Is it possible that multiple packets arrivng in quick succession might cause > data to get corrupted under some circumstances? I think yes, a new packet can overwrite an old one, that is why I have the IRQ check there. Best, Miklos > > > > Thanks, > > Lewis > > > > > > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Miklos > Maroti > Sent: Sunday, March 18, 2012 8:45 PM > To: Oldrine Lewis > Cc: [email protected] > Subject: Re: [Tinyos-help] IRIS motes corrupted data received - CRC check > > > > Hi Lewis, > > > > In the extended mode (which the RF230DriverHwAckP uses) all packets > > with an invalid CRC are discarded. The software ack driver > > (RF230DriverLayerP) does not use the RX_CRC_VALID flag because it was > > not present in the rev A of the chip. (Looking at the docs know I > > cannot find a record of this fact, maybe it was there but > > undocumented?) I am curious how you have seen corrupted messages. Can > > you have specific examples? Do you see them with the softwareack > > driver as well? > > > > Miklos > > > > On Sun, Mar 18, 2012 at 8:28 PM, Oldrine Lewis <[email protected]> wrote: > >> Hi, > >> > >> I have a simple test where one node broadcasts packets and it is received >> by > >> multiple nodes. I noticed that I was occassionally receiving some >> corrupted > >> packets. The packets were transmitted correctly because one of the other > >> nodes received the packet correctly. > >> > >> On doing a little investigation, I noticed that the lower layer driver > >> (RF230DriverHwAckP.nc) does not check the RX_CRC_VALID flag in the >> register > >> PHY_RSSI (0x06) which is updated with the result of the FCS check on the > >> received packet. > >> > >> > >> > >> Would adding another check improve the Receiver reliability? > >> > >> > >> > >> Thanks, > >> > >> Lewis > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> _______________________________________________ > >> Tinyos-help mailing list > >> [email protected] > >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
